1. Field of the Invention
The present invention generally relates to the protection and thermal management of equipment, and more particularly to a method of providing shock and vibration isolation for components that also require temperature control.
2. Description of the Related Art
Electronic equipment is often very susceptible to changes in operating temperatures, particularly warm temperatures. Excessive temperatures not only can result in a change in the response characteristics of certain electrical devices (such as semiconductor devices), but can further damage such devices beyond repair. Thermal management of electronic equipment has become even more difficult with the increasing miniaturization of electronic devices.
Components for computer systems can be particularly sensitive to high temperatures. For example, a typical hard disk drive (which is used to provide permanent storage of data for a computer system) has one or more circular disks supporting a magnetic medium, and uses a solenoid coil (referred to as a voice coil or VC coil) to actuate one or more arm assemblies that carry electromagnetic transducers or heads that read from, or write to, the disk. During periods of extended use, the electrical signals passing through the wires of the VC coil heat it up, which can lead to various problems. For example, a change in coil temperature affects the resistivity of the wire and therefore changes the electromagnetic response of the VC. Excessive heating of the VCM coil can also result in overheating of other sensitive components of the hard disk drive (HDD).
HDDs are usually packaged in a modular enclosure so that they may be easily installed in and removed from the computer system. Hermetically sealed enclosures are often preferred since they provide protection against air borne contaminants, but these types of enclosures preclude meaningful air circulation around the disk, resulting in a dramatic temperature increase between the external cooling air and the disk surfaces. Some HDD enclosures are not totally sealed as they use "breather" filters which allow the pressure inside the enclosure to equilibrate with ambient pressure, such as where ambient pressure changes due to temperature or altitude, but breather filters do not allow any appreciable air flow. The problem of VCM coil cooling is further exacerbated by the increasingly diminutive size of HDD enclosures. Even techniques that provide some internal air flow within the enclosure still require transfer of excess heat from the enclosure to the outside air. Such heat transfer is typically provided by attaching some type of heat sink article to the exterior of the enclosure to provide improved thermal conductivity. Finally, ruggedizing commercial, off-the-shelf (COTS) disks require that the enclosure as designed be placed within another hermetic canister for protection from corrosive and caustic environments, such as condensing humidity, salt fog, airborne sand and dust, fuels and hydraulic fluids. This obviously compounds an already difficult thermal management problem.
Furthermore, electronic equipment is also often sensitive to minor impacts or intense vibrations which can affect moving parts of a component. Considering again the example of a hard disk drive, these units generally require enhanced shock and vibration isolation, especially for use in automotive, industrial, aerospace, and military environments. Excessive movement of the actuator assembly can result in a "crash" of the HDD, leading to critical loss of data. One type of shock and vibration isolator that is commonly used consists of an elastomeric element which is provided within the enclosure, i.e., the component is supported by the elastomeric element which is further attached to the interior of the enclosure. The other type of isolator that is most frequently used is a wire rope or cable mount. While these elements can achieve substantial isolation of the component from physical jarring, there is never complete protection from extreme impacts, so the term "isolation" should not be construed as connoting absolute suppression of mechanical vibrations or shocks.
Vibration isolation and thermal conductivity are mutually exclusive qualities in currently available computer mounting components. Due to the relative motion required between the hardware and its mounting surfaces for proper vibration isolation, thermal grounding techniques have been generally insufficient. Attempts have been made to implement an isolation system outside the hermetic enclosure, with snubbers and copper foil provided within the enclosure to enhance shock resistance and heat transfer, but this approach provides relatively poor thermal protection. It would, therefore, be desirable to provide a method of shock and vibration isolation that included an acceptable thermal path between a component and its enclosure. It would be further advantageous if the method did not require any additional parts, assemblies, or processes.